复合材料液体模塑成型工艺中预成型体渗透率张量的数值预测

结合均匀化理论和计算流体动力学技术, 实现了对复合材料液体模塑工艺中预成型体渗透率张量的预测。首先, 采用均匀化理论分析了流体在多孔介质内的流动问题, 推导出广义达西定律, 证明以施加周期性边界条件的单胞为研究对象, 可以预测预成型体的渗透率张量, 并以单向纤维织物为例, 对该方法进行了验证。对于复杂结构的预成型体, 渗透率的预测分为两步, 首先分别确定预成型体中流道和纤维束的渗透率, 然后计算其整体宏观渗透率。对于二维平面织物, 该方法与其他预测方法及实验的结果吻合较好。本文还考察了单胞的微观结构对渗透率的影响, 微观结构相似的预成型体如果孔隙率相同, 但束间流道的结构不同, 其整体宏观渗透率也存在很大差别。 

Numerical prediction of saturated permeability tensor of a woven fabric for use in the fluid simulation of liquid composite molding

The saturated permeability tensor of composite preforms was predicted by the combination of homogenization theory and computational fluid dynamics technique. Generalized Darcys law was first derived from the study of fluid flow through a solid-fluid mixture, and the saturated permeability tensor of a preform could be predicted by studying its unit cell under periodic boundary conditions. The efficiency of this method was validated by conventional analytical methods for unidirectional fabrics. For preforms with complex microstructure, the permeability prediction involved two steps. First, the effective permeability values of the open channel and tows of the unit cell were determined respectively, and the overall permeability was determined accordingly. For a plane-weave fabric, the results obtained here are in good agreement with other methods and experimental results. The effects of unit cell microstructure were also investigated. The analyses show that the permeability values may differ from each other significantly for preforms with equal porosities, similar microstructures but different inter-tow channel configurations.